1. Field
The present disclosure relates to an ion beam source.
2. Description of the Related Art
An ion beam source is a device that generates ions in a plasma shape by using ionized gas and emits the generated ions in a beam shape, which is an important component in a thinfilm process. The ion beam emitted from the ion beam source can be used to perform processes of surface modification, surface cleaning, pre-processing, assisted deposition of thinfilm, etching, post-processing, and the like. The ion beam source forms a closed loop (closed drift loop) using electrodes and magnetic poles and transfers electrons along the closed loop at high speed. The closed loop, in which the electrons are transferred, is continuously provided with ionization gas from outside for generating the ions.
U.S. Pat. No. 7,425,709 discloses an ion beam source including a gas supply tube for supplying ionization gas to the inside, i.e., backward of an electrode, an electrode that allows cooling water to flow therein, and an interval adjustment screw for maintaining an interval between the electrode and the magnetic pole constant, in order to solve problems of dissipating heat generated from the inside and keeping plasma uniformity constant.
However, such an ion beam source causes etching phenomenon in a direction of the internal electrode surface during the ionization processing under plasma and causes substrate contamination as etched impurities moves along with the generated ions to a substrate by pressure difference. Further, particles in emission area are attached on the electrode and generate an electric arc on the electrode. The generation of such impurities and the generation of the arc degrade the ionization capability of the ion beam source, affecting a continuous research for long time and a post-processing.
U.S. Pat. No. 6,750,600, U.S. Pat. No. 6,870,164, KR Pub. No. 10-2011-0118622 describe methods of changing the polarity of the electrode.